contractcheck does not work together with braiding symbols

[Gertian]

Contractcheck doesn't seem capable of dealing with planar contractions containing the tau symbol. The following provides a MWE :

sp = ℂ^2
T = TensorMap(rand, ComplexF64, sp, sp)

a = @planar opt=true T[1;2]*T[2;1]
b = @planar opt=true T[1;4]*T[3;2]*τ[4 1;2 3]

c = @planar contractcheck=true opt=true T[1;2]*T[1;2]    #works as expected
b = @planar contractcheck=true opt=true T[1;4]*T[3;2]*τ[4 1;2 3] #ERROR: UndefVarError: `τ` not defined

[Jutho]

Good catch; will have to look into this.

[Gertian]

Thanks, that would be super helpful !